I really can't see Sheik returning to this - everything LoZ-related has been focussed on Twilight Princess.

I don't think Young Link will be in either, because he's too much of a clone.

Mr Game and Watch should NOT be in the game. That would be horrible. I hated him in Melee, and I don't want him in Brawl. As Frogger says, who likes him, anyway? I can't imagine too many people having him as the character they use the most.